Thorombospondin-1 (TSP-1) is a 450 kDa extracellular matrix glycoprotein, with anti-angiogenic activity. We analyzed the relationship in TSP-1 expression and Microvessel count (MVC), and also clinical factors, using immunohistochemical methods for non-small cell cancer (NSCLC). Histopathologically, there was inverse correlation between TSP-1 expression and MVC for squamous cell carcinoma, but not for adenocarcinoma cases. Among 199 completely resected cases of NSCLC, the 5-year survival was 77.0% when the expression of TSP-1 was maintained and 55.1% when the expression were reduced, respectively (P=0.0046). When compared with TSP-1 expression in the high MVC subgroup, there was significantly shorter survival time when TSP-1 expression was reduced (P=0.0091), and no significant difference was seen for the low MVC subgroup. Multivariate analysis revealed that expression of TSP-1 is as a prognostic factor of NSCLC. Our present data suggest that TSP-1 might not be a direct anti-angiogenic factor and the TSP-1 expression is a prognostic indicator of NSCLC.